As optical systems continue to increase the volume and speed of information communicated, the need for methods and apparatus operable to facilitate high speed optical signal processing also escalates. Information providers make significant investments in communication equipment only to have that equipment become obsolete as the demand for increased bandwidth quickly swamps the equipment's capacity. Information providers, therefore, value enhancements to existing equipment that can extend the viability of that equipment at a fraction of the cost of replacement.
Overview of Various Example Embodiments
The present invention recognizes a need for a method and apparatus operable to efficiently and effectively facilitate high speed optical routing. At least some aspects of this invention facilitate increasing switching speed, thereby increasing system bandwidth, without the need to completely replace existing system infrastructure. Various aspects of the invention can also be applied to new equipment designs, rendering those designs more cost efficient and desirable to information providers.
In one embodiment, a router comprises a star switching fabric operable to receive a plurality of optical signals each having a wavelength and each associated with a payload received by the router and to communicate from the switching fabric a plurality of substantially similar sets of the optical signals. The router further comprises a plurality of tunable filters each having a configuration speed and each associated with a communication path coupled to one of a plurality of destination elements. Each filter is operable to receive one of the sets of optical signals from the switching fabric and to selectively tune to a wavelength of one of the plurality of optical signals received to facilitate communication of at least the payload associated with that optical signal toward the destination element associated with that filter. The router also comprises a plurality of line cards operable to facilitate generation of at least some of the optical signals for transmission to the star switching fabric. At least one of the plurality of line cards comprises a switching enhancer operable to increase the switching speed of the router without modifying the configuration speed of any of the tunable filters.
In one particular embodiment, the switching enhancer comprises an aggregator operable to combine information from a plurality of packets associated with a common output communication path into an aggregated frame.
In another embodiment, the switching enhancer comprises an optical transmitter operable to receive an electrical signal representing a packet received by the line card having an original duration and to generate a packet representing the received packet but having a shortened duration compared to the original duration.
In still another embodiment, the switching enhancer comprises a plurality of tunable filters associated with a single output optical link from the router and operable to receive one of the sets of optical signals from the star switching fabric. At least one of the plurality of tunable filters is operable to reconfigure while another of the plurality of tunable filters processes a signal received from the star switching fabric.
In yet another embodiment, the switching enhancer comprises a plurality of tunable optical transmitters associated with a single input optical link to the router and operable to generate at a selected wavelength one of the optical signals for transmission to the star switching fabric. At least one of the plurality of tunable transmitters is operable to reconfigure without emitting light while another of the tunable transmitters generates a signal for transmission to the star switching fabric.
In still another embodiment, the switching enhancer comprises an express lane associated with at least one of the plurality of filters, wherein the express lane bypasses all of the plurality of line cards.
Any of these switching enhancing enhancements could be combined with any one or more of the other enhancements to further increase the speed of the router.
Depending on the specific features implemented, particular embodiments may exhibit some, none, or all of the following technical advantages. One embodiment provides one or more novel switching enhancing mechanisms in connection with routing optical signals using a star switching fabric.
In some embodiments, associating a plurality of tunable filters with one or more output links from the router provides an advantage of allowing one or more of the plurality of filters to retune to other wavelengths while another of the plurality processes a signal from the switching fabric. Likewise, in these or other embodiments, associating a plurality of tunable filters with a single input port to the router allows one or more of the plurality of transmitters to retune to other wavelengths while another of the plurality of transmitters generates, based on a signal received at the input port, a signal for transmission to the switching fabric at a different wavelength. These techniques hide switching delays that would otherwise occur when waiting for tunable filters and/or transmitters to reconfigure to process another wavelength.
Implementing express channels can provide significant advantages in avoiding unnecessary processing of particular groups of optical signals that require no electronic signal processing. Aggregation of packets within the router reduces the number of switching operations the tunable elements undertake, further increasing the speed of the router. Similarly, reducing the duration of the packets traversing the router helps speed the router's operation.
Some embodiments use tunable lasers and fixed wavelength transmitters. These embodiments provide an advantage of minimizing cost by implementing low cost tunable filters as compared to relatively higher cost tunable lasers. In addition, implementing tunable filters readily facilitates multicast and/or broadcast operation simply by provisioning a plurality of the tunable filters to receive a particular optical router signal communicated from the switching fabric.
Other technical advantages are readily apparent to one of skill in the art from the attached figures, description, and claims.